Symptoms of an Intake Leak?

KnuckleDuster said

Thanks.
TXDart and checked the radiator neck with an emissions sniffer whle the car was running, got zero readings. I think that ruled out a head gasket.
Tried three radiators, currently running a 26" 3 row brass I had rodded and checked. 7 blade OE vicious clutch fan with a factory shroud. Sealed the gaps between the radiator and shroud as well as hood to core support.

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Could be air pockets in there, might try and bleed the system?

Have a thermostat? What temp?

Do you have any under driven pulleys?

Could there be crud in the coolant passages?

Regardless of the cooling situation, I think you might want to take some timing out. Not sure how radical your combo is but 20 initial seems like a lot. As an example, I had a high strung 340/W2 with a .557" solid cam that idled at 1,100. Had 18 initial. If your timing was excessively advanced then you would be melting stuff.

It's worth a shot. It's easy to do and you can always put it back.